Project Summary: The Vulnerable Aging Recruitment and Retention Core (VARC) Older adults are vastly underrepresented in research. This underrepresentation is even more pronounced for older adults with medical vulnerability (e.g., cognitive impairment and complex multi-morbidity) and/or social vulnerability (e.g., isolation, poverty, limited literacy or homelessness). These medical and social vulnerabilities often coexist and interact to produce profound effects on disease incidence, progression, outcomes, and response to health interventions. Yet older adults with these vulnerabilities are often difficult to recruit and retain, adversely affecting their representation in research and impairing our knowledge of how best to optimize their care. The UCSF Division of Geriatrics has an international reputation for expertise in the recruitment, retention, and protection of vulnerable older adults in research including in longitudinal cohorts and randomized trials. In our first cycle, the UCSF Older Adults Independence Center (OAIC) greatly expanded its support of the recruitment and retention of vulnerable older adults across UCSF. To build on this progress and meet the increased demand for our expertise, we propose to create a dedicated core: The Vulnerable Aging Recruitment and Retention Core (VARC). We propose the following aims: 1) Provide expert consultation for the design (e.g., pilots, longitudinal cohorts, and efficacy and pragmatic trials) and Institutional Review Board considerations for primary data collection studies that focus on older adults with medical and/or social vulnerabilities; 2) Support OAIC investigators on methods for recruiting, enrolling, and retaining vulnerable older adults, including appropriate informed consent procedures and the creation of community advisory boards; 3) Establish administrative, mentorship and educational resources to train OAIC-affiliated researchers and staff concerning the logistics of recruitment, enrollment, and consent of vulnerable populations; 4) Advise on the incorporation of predictor and outcome measures of medical vulnerability (e.g., cognitive impairment, frailty) and social vulnerability (e.g., health literacy, poverty, social isolation, etc.) in collaboration with the Data and Analysis Core. 5) Support development projects that create novel methods for improving recruitment and retention of vulnerable older adults into research studies.